AAT3104 Datasheet, PDF(8/15 Page) Advanced Analogic Technologies – Low Cost 1x/2x 4 Channel Charge Pump WLED Driver

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AAT3104 Datasheet, PDF (8/15 Pages) Advanced Analogic Technologies – Low Cost 1x/2x 4 Channel Charge Pump WLED Driver

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ChargePumpTM

PRODUCT DATASHEET

AAT3104178

Low Cost 1x/2x 4 Channel Charge Pump WLED Driver

Functional Block Diagram

C+ Câ

OUT

EN/SET

Two-Mode

CP Control

VF Monitoring

S2Cwire Control

IREF

5 Bits DAC

GND

Functional Description

The AAT3104 is a low-cost charge-pump solution

designed to drive up to four white LEDs. The charge

pump operates from a 2.7V to 5.5V power source and

converts it to voltage levels necessary to drive the LEDs.

LED current is individually controlled through integrated

current sources powered from the output of the charge

pump. Low 1x charge-pump output resistance and low-

drop voltage current sources allow the charge pump to

remain in 1x mode with an input voltage as low as 3.8V

and LED forward voltages of 3.5V. Once in 2x mode, the

charge pump monitors the input supply voltage and

automatically switches back to 1x mode when there is

sufficient input voltage.

The AAT3104 requires only three external components:

one 1Î¼F ceramic capacitor for the charge pump flying

capacitor (CP), one 1Î¼F ceramic input capacitor (CIN), one

1Î¼F ceramic output capacitor (COUT). The four constant

current outputs of the AAT3104 (D1 to D4) can drive four

individual LEDs with a maximum current of 30mA each.

AnalogicTechâs S2Cwire serial interface enables the

AAT3104-1/-2 and changes the current source magni-

tudes through the EN/SET pin.

S2Cwire Serial Interface

The LED output current of the AAT3104 is controlled by

AnalogicTechâs S2Cwire serial interface. Since the LED

current is programmable, no PWM or additional control

circuitry is needed to control LED brightness. This feature

greatly reduces the burden on a microcontroller or sys-

tem IC to manage LED or display brightness, allowing the

user to âset it and forget it.â With its high-speed serial

interface (1MHz data rate), the LED current can be

changed quickly and easily. Also, the non-pulsating LED

www.analogictech.com

3104.2008.09.1.0

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